;
(function(window, undefined) {

	"use strict";

	// Helper functions.
	var getContext = function(width, height) {
		var canvas = document.createElement("canvas");
		canvas.setAttribute('width', width);
		canvas.setAttribute('height', height);
		return canvas.getContext('2d');
	};

	var getImageData = function(img, loaded) {

		var imgObj = new Image();
		var imgSrc = img.src || img;

		// Can't set cross origin to be anonymous for data url's
		// https://github.com/mrdoob/three.js/issues/1305
		if (imgSrc.substring(0, 5) !== 'data:')
			imgObj.crossOrigin = "Anonymous";

		imgObj.onload = function() {
			var context = getContext(imgObj.width, imgObj.height);
			context.drawImage(imgObj, 0, 0);

			var imageData = context.getImageData(0, 0, imgObj.width, imgObj.height);
			loaded && loaded(imageData.data);
		};

		imgObj.src = imgSrc;

	};

	var makeRGB = function(name) {
		return ['rgb(', name, ')'].join('');
	};

	var mapPalette = function(palette) {
		var arr = [];
		for (var prop in palette) {
			arr.push(frmtPobj(prop, palette[prop]))
		};
		arr.sort(function(a, b) {
			return (b.count - a.count)
		});
		return arr;
	};

	var fitPalette = function(arr, fitSize) {
		if (arr.length > fitSize) {
			return arr.slice(0, fitSize);
		} else {
			for (var i = arr.length - 1; i < fitSize - 1; i++) {
				arr.push(frmtPobj('0,0,0', 0))
			};
			return arr;
		};
	};

	var frmtPobj = function(a, b) {
		return {
			name: makeRGB(a),
			count: b
		};
	}


	// RGBaster Object
	// ---------------
	//
	var PALETTESIZE = 10;

	var RGBaster = {};

	RGBaster.colors = function(img, opts) {

		opts = opts || {};
		var exclude = opts.exclude || [], // for example, to exclude white and black:  [ '0,0,0', '255,255,255' ]
			paletteSize = opts.paletteSize || PALETTESIZE;

		getImageData(img, function(data) {

			var colorCounts = {},
				rgbString = '',
				rgb = [],
				colors = {
					dominant: {
						name: '',
						count: 0
					},
					palette: []
				};

			var i = 0;
			for (; i < data.length; i += 4) {
				rgb[0] = data[i];
				rgb[1] = data[i + 1];
				rgb[2] = data[i + 2];
				rgbString = rgb.join(",");

				// skip undefined data and transparent pixels
				if (rgb.indexOf(undefined) !== -1 || data[i + 3] === 0) {
					continue;
				}

				// Ignore those colors in the exclude list.
				if (exclude.indexOf(makeRGB(rgbString)) === -1) {
					if (rgbString in colorCounts) {
						colorCounts[rgbString] = colorCounts[rgbString] + 1;
					} else {
						colorCounts[rgbString] = 1;
					}
				}

			}

			if (opts.success) {
				var palette = fitPalette(mapPalette(colorCounts), paletteSize + 1);
				opts.success({
					dominant: palette[0].name,
					secondary: palette[1].name,
					palette: palette.map(function(c) {
						return c.name;
					}).slice(1)
				});
			}
		});
	};

	window.RGBaster = window.RGBaster || RGBaster;

})(window);
